For the treatment of cancer, surgical therapy, radiation therapy and chemotherapy are mainly employed. However, no satisfactory therapeutic results have been obtained with respect to recurrence and metastasis of cancer. Most of anti-cancer drugs presently available are designed to kill tumor cells by impairing biosynthesis of nucleic acids or proteins. However, in their activities, such anti-cancer drugs do not distinguish normal cells from tumor cells. Accordingly, there has been a serious problem that side effects are likely to result due to their cytotoxity against normal cells. Moreover, such anti-cancer drugs are designed to reduce the primary focus for the treatment. However, metastasis of tumor cells has been a problem in the treatment of cancer. Namely, tumor cells leave from the primary site and move to other organs and proliferate there, thus leading to poor prognosis. Accordingly, for the fundamental treatment of cancer, it is desired to develop an anti-cancer drug which exhibits effective inhibiting activities not only against proliferation of tumor cells but also against invasion and metastasis of tumor cells.
Many studies have been made on the mechanism of metastasis of cancer, and searches for anti-metastatic substances have been widely conducted. Tumor cells released from the primary focus, will enter into a blood vessel. Then, the cells will adhere to the vascular wall and then penetrate underneath the vascular endothelial cell layer, and they will destroy the extracellular matrix and invade into the parenchyma of the target organ. In this way, tumor cells are believed to metastasize (L. A. Liotta et al., lab. Invest., 49,636-649, (1983)). It is believed that for the development of a drug for metastasis of tumor cells, a substance should be developed which controls any one of the above-mentioned steps. For example, it may be a substance which inhibits adherence of the tumor cells to the extracellular matrix (e.g. N. J. Humphries et al., Science, 223, 467-470 (1986)), a substance which inhibits the penetration underneath the mesothelial cell layer or underneath the vascular endothelial cell layer (e.g. Isoai et al., Jpn. J. Cancer Res., 81, 909-914 (1990)) or a substance which inhibits the destruction of the extracellular matrix (e.g. R. M. Schultz et al., Cancer Res., 48, 5539-5545 (1988)).